Rotary motor or pump

ABSTRACT

A FLUID MOTOR OR PUMP OF THE ORBITING GEROTOR TYPE IN WHICH VALVING IS ACCOMPLISHED THROUGH THE USE OF RECIPROCATING PISTONS. THE PISTONS ARE SELECTIVELY RECIPROCATED IN RESPONSE TO EITHER RELATIVE ORBITAL MOVEMENT OR RELATIVE ROTATION BETWEEN THE ROTOR AND STATOR TO CONNECT THE FLUID INPUT WITH EXPANDING GEROTOR CHAMBERS AND FLUID OUTPUT WITH CONTRACTING GEROTOR CHAMBERS. THE PISTONS MAY BE   DISPOSED FOR RECIPROCATION ON AN AXIS RADIAL TO THE LONGITUDINAL AXIS OF THE GEROTOR UNIT, OR THEY MAY BE DISPOSED FOR RECIPROCATION ON AN AXIS PARALLEL TO AND SPACED FROM THE LONGITUDINAL AXIS OF THE GORETOR UNIT.

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United States Patent O sota Filed Dec. 15, 1969, Ser. No. 885,187 Int. Cl. F01c N02 US. Cl. 418-61 16 Claims ABSTRACT OF THE DISCLOSURE A fluid motor or pump of the orbiting Gerotor type in which valving is accomplished through the use of reciprocating pistons. The pistons are selectively reciprocated in response to either relative orbital movement or relative rotation between the rotor and stator to connect the fluid input with expanding Gerotor chambers and fluid output with contracting Gerotor chambers. The pistons may be disposed for reciprocation on an axis radial to the longitudinal axis of the Gerotor unit, or they may be disposed for reciprocation on an axis parallel to and spaced from the longitudinal axis of the Gerotor unit.

BACKGROUND OF THE INVENTION The invention relates to the field of rotary motors, pumps, or metering devices which utilize the orbiting Gerotor principle. The invention resides, more particularly, in a piston type valving means for conducting pressure fluid into expanding Gerotor chambers and for conducting fluid exhaust from contracting Gerotor chambers.

The Gerotor principle is well known in the art of fluid motors, pumps, and metering devices and has been employed in a wide variety of hydraulic motors that have enjoyed some measure of commercial success. As is Well known in the art, with a fixed stator or outer Gerotor ring, the rotor or star element both orbits and rotates inside the stator thereby defining expanding and contracting Gerotor chambers. It should be recognized that the expanding and contracting Gerotor chambers are themselves constantly revolving about a central axis and, consequently, fixed porting in the Gerotor housing is not a solution to the valving problem. The art has proposed various means for valving fluid pressure into the expanding Gerotor chambers and conducting fluid exhaust from the contracting Gerotor chambers. In large measure, valving has been accomplished by rotary or commutating valve spools, such as those disclosed in Charlson Pat. Re. 25,291, reissued Dec. 4, 1962 (original No. 2,821,171) and Hudgens Pat. 3,289,602, issued Dec. 6, 1966. In addition to commutating valve spools, a single orbiting valve ring with a fluid conducting annulus has been proposed in Charlson Pat. 3,316,814, issued May 2, 1967.

. ing adjustment. The present invention represents a design in which timing may be conveniently adjusted to coordinate valving with Gerotor position.

SUMMARY The present invention is characterized by a series of piston valves corresponding in number to the number of Gerotor chambers disposed about the longitudinal axis of the fluid motor or pump. The piston valves may be disposed for reciprocation on respective axes radial to the longitudinal axis of the motor or pump, or they may be disposed for reciprocation on an axis spaced from and parallel to the longitudinal axis. Camming means responsive to the relative movement of the rotor and stator are provided for reciprocating the pistons to selectively conduct fluid pressure into expanding Gerotor chambers and fluid exhaust from contracting Gerotor chambers.

The primary object of the present invention is to provide a rotary motor, pump or metering device of the orbiting Gerotor type wherein valving is-accomplished by reciprocating pistons actuated in response to relative movement, either relative rotation or orbital movement, between the rotor and stator.

DESCRIPTION OF DRAWINGS FIG. 1 is a sectional view of the fluid motor or pump which comprises the present invention taken on the line 11 of FIG. 3.

FIG. 2 is a sectional view of the Gerotor unit taken on the line 22 of FIG. 1 and is somewhat reduced in size.

FIG. 3 is a sectional view taken on the line 3+3 of FIG. 1 and shows the piston valves and their radial mounting in the piston valve cylinder plate.

FIG. 4 is a sectional view taken on the line 4-4 of FIG. 1 and shows the end plate with annular grooves for fluid input, fluid exhaust, and O-ring mounting.

FIG. 5 is a sectional view taken on the line 5-5 of FIG. 4 and shows the end plate including the fluid input and exhaust connections, the fluid input and exhaust internal grooves and their communication respectively with the fluid input and exhaust connections, and the O-ring mounting groove.

FIG. 6 is a sectional view taken on the line 66 of FIG. 1 and shows the piston valve cylinder plate and the relationship between the piston valves and the cylinder plate valve openings.

FIG. 7 is a sectional view taken on the line 77 of FIG. 6.

FIG. 8 is a sectional view taken on the line 8--8 of FIG. 1 and shows the Gerotor chamber aperture and wear plate.

FIG. 9 is an end view of the eccentric circular cam and shows the relationship between the eccentric piston valve camming surface and the actuating crank slot.

FIG. 10 is a sectional view of a partially shown second embodiment of the present invention whereby piston actuation is accomplished through the use of a star-shaped cam.

FIG. 11 is a somewhat schematic sectional view of a partially shown third embodiment of the present invention and shows the piston valves mounted for reciprocation on an axis parallel to and spaced from the longitudinal axis of the Gerotor unit, and radially mounted rollers for piston valve actuation. The section shown is taken on the line 1111 of FIG. 12.

FIG. 12 is a sectional view taken on the line 12--12 of FIG. 11.

FIG. 13 is a somewhat schematic view of a partially shown fourth embodiment of the present invention and shows an undulated cam for piston valve actuation.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The first embodiment of the present invention consisting of radially mounted pistons and an eccentric circular cam is shown in detail in FIGS. 1-9. A second embodiment wherein the radially mounted pistons are actuated by a star-shaped cam is partially shown in FIG. 10. A third embodiment consisting of pistons mounted for reciprocation on an axis spaced from and parallel to the longitudinal axis of the Gerotor unit, and radially mounted 3 rollers for piston actuation, is partially and somewhat schematically shown in FIGS. 11 and 12. A fourth embodiment is partially shown in FIG. 13 wherein the axially mounted pistons are actuated by an undulated cam.

The general nature of the first embodiment may be understood with reference first to FIG. 1. The fluid motor includes a generally cylindrical housing 21, having a mounting flange 21a and an internal flange 21b, end plate 23, and end cap 24. End plate 23 is mounted to housing 21 by means of machine screws 25. End cap 24 is mounted to the opposite end of housing 21 by means of machine screws 26.

A conventional Gerotor unit 30, shown in FIGS. 1 and 2, includes an internally toothed outer ring or stator 31 and an externally toothed star or rotor 32. Rotor 32 is formed with one less external projection than the number of internal projections or lobes of stator 31 to define, in the conventional manner, a series of Gerotor cavities 33. Rotor 32 both orbits and rotates in stator 31 thereby causing chambers 33 to expand and contract, all in the conventional manner.

As shown in FIG. 1, output shaft is mounted in bearings 41 which are in turn mounted in housing 21. The longitudinal axis of shaft 40 defines the longitudinal axis of the fluid pump or motor 20 and includes an internally splined tubular portion 40a, flange 40b, shoulder 40c, and a key slot 40d. Shaft 40 is mounted with flange 40b in contact with one bearing 41 by means of spacer ring 42 which extends from flange 40b to the other bearing 41, as shown in FIG. 1.

In the conventional manner, relative rotation, but not orbital movement, of rotor 32 with respect to stator 31 is transferred to output shaft 40 by means of short shaft 45 which is arcuately externally splined at each end. Short shaft 45 is commonly referred to in the art as the dogbone. More particularly, short shaft 45 is formed with arcuate external spline 45a at one end which mesh with internal spline 40a of shaft 40, and with arcuate external spline 45b at the other end which mesh with internal spline 32a of rotor 32. Thus, rotation (but not orbital movement) of rotor 32 with respect to stator 31, causes rotation of output shaft 40 and vice versa.

Wear plate which includes a central aperture 50a is mounted between internal flange 21b of housing 21 and Gerotor unit 30.

All of the foregoing elements are conventional. The novel aspect of the present invention resides in the provision of reciprocating pistons for valving fluid input and exhaust to the respective sequentially expanding and contracting chambers 33 of Gerotor unit 30 and a detailed understanding of the elements related to the piston valving may be obtained with reference to FIGS. 1 and 3-8. With reference first to FIG. 1, a series of piston valves are radially disposed about the longitudinal axis of shaft 40 in piston valve cylinder plate 61. As shown in FIG. 1 and FIG. 3, pistons 60 are provided with a longitudinal bore 60a which includes an enlarged portion for seating spring 62 and a small portion which serves to vent fluid from one end of piston 60 to the other. Pistons 60 are formed with a neck portion 60b which provides a movable fluid passage 63 to allow fluid passage from one side of piston 60 to the other.

With reference to FIG. 3, pistons 60 are mounted in radial bores or cylinders 61a of cylinder plate 61. As best seen in FIG. 6, cylinder plate 61 also defines an elongated fluid input aperture 61b serving each of the cylinders 61a and a fluid exhaust aperture 610 for each of the cylinders 61a.

Fluid input aperture 61b and fluid exhaust aperture 610 communicate with the fluid input connection and fluid exhaust connection of end cap 24, as will be described more particularly below. As shown in FIGS. 1 and 3, cylinder plate 61 is provided with seven circular cylinder plate chamber apertures 61d. Cylinder plate chamber apertures 61d serve as both fluid input and fluid exhaust passages depending upon the position of piston 60 in cylinder 61a which governs the position of movable fluid passages 63. Thus, cylinder plate chamber aperture 61d is either in connection with passage 61b or 610 depending upon the position of piston 60.

A second wear plate 65, shown in FIG. 8, is provided between cylinder plate 61 and Gerotor unit 30. Wear plate 65 is provided with seven circular chamber apertures 65a which register with cylinder plate chamber aperture 61d and with chambers 33 of Gerotor unit 30, as shown in FIGS. 1 and 2 respectively.

Pressure fluid and exhaust fluid is directed to fluid input passages 61b and fluid exhaust passage 610 through end cap 24 by means of cross bores and annular grooves, best seen in FIGS. 1, 4 and 5. With reference to FIGS. 4 and 5, end cap 24 includes a fluid input threaded cross bore 24a and a similar threaded fluid exhaust cross bore 24b. Fluid input bore 24a connects with annular fluid input groove 240 through passage 24d. Fluid output bore 24b connects with fluid output annular groove 24e through passage 24f. Fluid input or pressure groove 240 is sealed from fluid output or exhaust groove 242 through the provision of O-ring 25 (see FIG. 1) seated in annular groove 24g.

As best seen in FIG. 1, pressure groove 24c registers with each of the seven fluid input passages 61b of cylinder plate 61 and exhaust groove 242 registers with each of the seven fluid exhaust passages 610. Thus, with properly timed positioning of each of the pistons 60 with respect to the Gerotor unit 30, input fluid is directed from fluid input bore 24a, through passage 24d, into pressure groove 240, through three of the fluid input passages 61b, around the neck 60b of piston 60, through three of the cylinder plate chamber apertures 61d, through three of the chamber apertures 65a, and into the three expanding chambers 33 of Gerotor unit 30. Fluid exhaust is conducted from the three contracting chambers of Gerotor unit 30 through apertures 65a and 61d, around the neck 60b of piston 60, through fluid exhaust passages 61c, into exhaust grooves 242, through passage 24f and then through exhaust bore 241;. One of the pistons will be changing over from exhaust pressure and will not valve any fluid either into or out of its chamber in Gerotor unit 30.

The means for selectively operating pistons 60 to conduct or valve fluid pressure into expanding chambers 33 of Gerotor unit 30, and to conduct or valve fluid exhaust out of contracting chambers 33, may be readily understood with reference to FIGS. 1, 3, 6 and 9. With reference first to FIG. 1, eccentric circular camming means 70 is formed with circular bearing surface 70a which is mounted in wear plate 65 coaxially with shaft 40. Eccentric circular camming means 70 also includes flange portion 70b, eccentric circular camming surface 700, mounting shaft 70d, and actuating slot 70e. Mounting shaft 70d is rotatably mounted in end cap 24 at bushing or bearing 71.

The eccentricities present in eccentric circular cam 70 are shown in FIG. 9. Vertical axis AA and horizontal axis CC represent the primary axes. Circular bearing surface 70a, flange 70b, and mounting shaft 70d are concentric about the intersection of axis AA and axis CC. Actuating slot 70a is offset upwardly, in the view shown in FIG. 9, on axis AA a distance greater than the orbital diameter of rotor 32. Eccentric circular camming surface 70c is offset on axis CC, and is concentric about the intersection of axis BB and axis CC, as shown in FIG. 9. The angular distance in the eccentricity of actuating slot 702 and the eccentricity of circular camming surface 700 provides the proper valve timing with respect to the expanding and contracting chambers 33 of Gerotor unit 30. With reference to FIGS. 3 and 6, pistons 60 are caused to reciprocate as eccentric circular camming surface 70e orbits about the intersection of axis AA and axis CC, to thereby allow fluid passage from fluid input passages 61b into expanding chambers 33 and to conduct fluid from the contracting chambers 33 and out fluid exhaust passages 61c.

Eccentric circular camming means 70 is caused to rotate as a result of the orbiting of extension 450 of short shaft 45 as rotor 32 orbits. Thus, extension 45c of short shaft 45 cranks eccentric circular camming means 70 about its rotating axis and eccentric circular cam 70 completes one rotation for each orbit of rotor 32. Rotation of rotor 32, which also occurs with orbiting movement, has no effect upon eccentric circular camming means 70.

The embodiment shown in FIGS. 1-9, may be characterized as a low speed, high torque motor with a maximum speed of 500 rpm. and a maximum torque of 2,000 inch-pounds. In the embodiment shown and described, pressure input should be in'the range of 200- 1,500 psi. with a maximum volumetric flow of about gallons per minute. It should, of course, be recognized that the foregoing speed, torque, pressure and volumetric flow ranges are given only as an example in connection with the embodiment shown in FIGS. 1-9. These conditions and characteristics may vary greatly for different applications of the present invention without departing from its scope.

In the embodiment shown in FIGS. 1-9 it is possible to vary or adjust (within limits) the timing of pistons 60. This timing adjustment may be conveniently accomplished by rotating cylinder plate 61 with respect to wear plate 65 and Gerotor unit 30. The limits on this adjustment are represented by communication or registration of cylinder plate chamber apertures 61d and chamber apertures 65a of Wear plate 65, which cannot be destroyed or eliminated. Nevertheless, a certain limited timing adjustment may be made in a convenient and simple manner with the present invention.

The embodiment shown partially in FIG. 10 differs from the embodiment of FIGS. 19 in that a star cam 80 is provided in place of eccentric circular cam 70. Thus, the embodiment of FIG. 70 is characterized by star cam 80 which actuates radially disposed pistons 81. Star cam 80 rotates in response to rotation of the fluid motor output shaft (not shown) and may be keyed or rotationally fixed thereto to rotate with the output shaft in any conventional manner. Since star cam 80 rotates with the output shaft and with the rotor of the Gerotor unit (not shown), as distinguished from being actuated by orbiting of the rotor, it rotates at the rate of eccentric circular cam 70. Star cam 80 actuates pistons 81 at the same rate that pistons 60 are actuated by eccentric circular cam 70, however, because of the more pronounced camming surface represented by the star points as compared to the circular eccentricity of cam 70. Thus, it should be understood that star cam 80 may be substituted for eccentric circular cam 70 without departing from the scope of the present invention.

A third embodiment of the invention is shown somewhat schematically in FIGS. 11 and 12. This embodiment is characterized by seven pistons disposed for reciprocation on an axis parallel to the axis of the fluid motor or pump. Thus, pistons 90 are disposed in cylinder 91 of housing 92. Pistons 90 are each cross bored at 90a and longitudinally bored at 90b, which serves to seat spring 93.

Housing 92 defines fluid input connection 92a and fluid output connection 92b. Fluid input connection 92a communicates with annular groove or cavity 92c and fluid output connection 92b communicates with annular groove or cavity 92d. Thus, annular cavity 920 serves as a pressure cavity and annular cavity 92d serves as an exhaust cavity.

Pistons 90 are reciprocated by means of radially disposed rollers 95 which are mounted for revolution as shaft 96 rotates, and also mounted for rotation about an axis radial to the axis of shaft 96. As shaft 96 rotates,

' rollers 95 revolve, and rotate in contact with pistons 90 to cause reciprocation thereof. Reciprocation of pistons causes cross bore 90a to register with either pressure cavity 92c or exhaust cavity 92d to thereby, respectively, conduct fluid under pressure through bore 90b and passage 92e into the expanding chamber of Gerotor unit 97, and conduct exhaust fluid from the contracting chambers of Gerotor unit 97 through passage 92e, bore 90b, and into exhaust cavity 92d and exhaust connection 92b. Short shaft or dogbone 98 is provided in the conventional manner to rotate shaft 96 with relative rotation of Gerotor unit 97.

Thus, it should be understood that rollers may be substituted for the other camming means shown in FIGS. 9 and 10 and. described above, and the piston valves which characterize the present invention may be axially disposed as shown in FIGS. 11 and 12, all within the scope of the present invention.

FIG. 13 represents a fourth embodiment and is characterized by undulated cam 100 which is mounted to shaft 101 and keyed thereto by key 102 for rotation therewith. The undulated camming surface 100:: of undulated cam 1007engages axially mounted pistons (such as those shown in FIG. 11) to thereby cause reciprocation thereof in the manner described in connection with the third embodiment shown in FIGS. 11 and 12. Thus, it should be understood that undulated cam 100 may be substituted for rollers 95, all within the scope of the present invention.

Variations in the specific design of the present invention may be made without departing from its scope. In addition to varying the piston disposition and means for actuating the pistons as described in connection with the four embodiments disclosed, other changes in specific design may be made. By way of example only, springs 62 and 93 may be eliminated with their function accomplished with fluid pressure; fluid input and exhaust locations may be reversed; the number of Gerotor chambers and pistons may vary; and while the invention has been described primarily as a motor, it should be understood that the invention may be embodied in a pump or metering device as well. Other variations may also be made without departing from the scope of the invention which is to be limited'only by the following claims.

I claim:

1. In a fluid motor or pump having a housing which defines a fluid input cavity and a fluid output cavity, a shaft disposed in said housing for rotation about its longitudinal axis, a Gerotor unit including a rotor and a stator adapted for relative rotational and orbital movement about said longitudinal axis to thereby define expanding and contracting Gerotor chambers, and means for connecting said Gerotor unit to said shaft such that said relative rotational movement of said rotor and stator results in rotation of said shaft about said longitudinal axis and vice versa, the improvement which comprises:

a series of piston valves corresponding in number to the number of chambers in said Gerotor unit disposed about said longitudinal axis,

means responsive to said relative movement of said rotor and stator for reciprocating said pistons to selectively connect said expanding Gerotor chambers with said fluid input cavity and said contracting Gerotor chambers with said fluid output cavity.

2. The apparatus of claim 1 wherein said pistons are radially disposed for reciprocation on an axis radial to said longitudinal axis.

3. The apparatus of claim 2 wherein said means responsive to said relative movement of said Gerotor unit for reciprocating said pistons comprises an eccentric circular cam mounted for rotation about said axis.

4. The apparatus of claim 2 wherein said means responsive to said relative movement of said Gerotor unit for reciprocating said pistons comprises a starshaped cam having a series of radially extending projections numbering one less than the number of said pistons, mounted for rotation about said axis.

5. The apparatus of claim 1 wherein said pistons are disposed about said longitudinal axis for reciprocation on an axis parallel to and spaced from said longitudinal axis.

6. The apparatus of claim 5 wherein said means responsive to said relative movement of said Gerotor unit for reciprocating said pistons comprises a series of radially disposed rollers numbering one less than the number of said pistons, each mounted for revolution about said longitudinal axis and for rotation about an axis radial thereto.

7. The apparatus of claim 5 wherein said means responsive to said relative movement of said Gerotor unit for reciprocating said pistons comprises an undulated camming surface having a series of undulations numbering one less than the number of said pistons mounted for rotation about said longitudinal axis.

8. The apparatus of claim 3 wherein said means for connecting said Gerotor unit to said shaft comprises a link universally splined to said rotor at one end and to said shaft at the other end.

9. The apparatus of claim 8 wherein said camming means is rotated by orbital movement of said link.

10. The apparatus of claim 4 wherein said star-shaped cam is rotated about said longitudinal axis by the rotation of said shaft.

11. The apparatus of claim 6 wherein said radially disposed rollers are caused to revolve about said longitudinal axis by the rotation of said shaft.

12. The apparatus of claim 7 wherein said undulated camming surface is caused to rotate about said longitudinal axis by the rotation of said shaft.

13. The apparatus of claim 9 and means for maintaining said pistons in engagement with said camming means.

14. The apparatus of claim 10 and means for maintaining said pistons in engagement with said camming means.

15. The apparatus of claim 11 and means for maintaining said pistons in engagement with said camming means.

16. The apparatus of claim 12 and means for maintaining said pistons in engagement with said camming means.

References Cited UNITED STATES PATENTS Re. 25,291 12/1962 Charlson 91-56 2,095,255 10/1937 Holmes 91-498 2,162,771 6/1939 Winans 418-61 3,063,429 11/ 1962 Niemann 418-61 3,131,678 5/1964 Pel'as 418-61 3,286,698 ll/1966 Peras 418-61 3,359,950 12/1967 De Castelet 418-61 3,446,021 5/1969 Lech 418-61 MARK M. NEWMAN, Primary Examiner W. J. GOODLIN, Assistant Examiner 

